Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
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25 records were found.
Periodically poled lithium niobate (PPLN) has, in recent years, become a very useful and prominent material for use in optical parametric oscillators (OPO's) and other nonlinear optical devices. In synchronously pumped OPO's, the combination of high peak power from short pulse cw modelocked lasers and the large nonlinearity of PPLN, allows a very large parametric gain to be achieved. This, in turn, allows the use of convenient tuning elements, such as diffraction gratings, whose loss would be unacceptable for low gain cw devices. The strong frequency discrimination, of diffraction gratings, allows operation close to degeneracy, while still maintaining singly resonant operation (SRO). The attraction of operating around degeneracy is that due to the large parametric gain bandwidth, a broad tuning range can be conveniently achieved, witho...
The use of a diffraction grating as a frequency-selective reflector, has allowed a synchronously pumped optical parametric oscillator based on periodically poled lithium niobate to tune over a wide range, 1900-2300 nm around degeneracy (2094 nm), on a single periodically poled lithium niobate grating at a fixed temperature. The grating ensures stable singly resonant operation over the whole of this range except for a very narrow range at degeneracy, where doubly resonant behavior is evident. The extent of this narrow range, ~6 nm, is confirmed by analysis
In recent years periodically poled lithium niobate (PPLN) has become a very usefull and prominent material for use in optical parametric oscillators (OPO's) and other nonlinear optical devices. The large nonlinearity of PPLN, combined with the high peak power available ftom short pulse cw modelocked lasers allows a very large parametric gain to be achievable in synchronously pumped OPO's. Close to degeneracy the gain bandwidth of these devices becomes very large and, theoretically, it is possible to tune the output wavelengths over a very wide range while maintaining a fuced temperature and domain grating period. However, when OPO's are operated close to degeneracy, there is a tendency to display doubly-resonant oscillation (DRO), with its well-known undesirable features of amplitude and frequency instability. We propose the use of a d...
Periodically poled lithium niobate (PPLN) has, in recent years, become a very useful and prominent material for use in optical parametric oscillators (OPO's) and other nonlinear optical devices. In synchronously pumped OPO's, the combination of high peak power from short pulse cw modelocked lasers and the large nonlinearity of PPLN, allows a very large parametric gain to be achieved. This, in turn, allows the use of convenient tuning elements, such as diffraction gratings, whose loss would be unacceptable for low gain cw devices. The strong frequency discrimination, of diffraction gratings, allows operation close to degeneracy, while still maintaining singly resonant operation (SRO). The attraction of operating around degeneracy is that due to the large parametric gain bandwidth, a broad tuning range can be conveniently achieved, witho...
Periodically-poled lithium niobate (PPLN) is proving to be a very versatile and effective nonlinear optical material. It has a high nonlinearity (20pm/V) and offers non-critical phase-matching over its entire transmission range. In the first experiments demonstrating synchronously-pumped parametric oscillation in PPLN, the tuning range achieved using a 1047nm pump (from a mode-locked Nd:YLF laser) covered 1.67µm - 2.806µm (signal+idler), using 6mm long PPLN samples that we had fabricated by electric field poling. In the experiment reported here, we have used longer samples (19mm, fabricated by Crystal Technology). This has resulted in lower thresholds, now down to as low as ~8mW of mean pump power at 1047nm. We have also used shorter grating periods, thus allowing a considerable extension of tuning range, now covering 1.33µm - 4.81µm. ...
A cw synchronously-pumped optical parametric oscillator, using periodically-poled lithium niobate has operated efficiently out to 4.81µm (signal 1.33µm). Available idler power at 4.81µm was 40mW average (100W peak), for ~1 W of 1047nm pump
We demonstrate the generation of compressed. transform-limited 250-fs pulses, tunable in the near infrared, by means of synchronously pumped optical parametric oscillation in periodically poled lithium niobate. The almost 20-fold compression from the 4-ps pulse duration of the cw mode-locked Nd:YLF pump results in signal peak powers well in excess of the pump power
The very high gains, achieved when using mode-locked pulses to synchronously pump an optical parametric oscillator based on periodically poled lithium niobate, permit oscillation even with strong idler absorption. Oscillation has been achieved at idler wavelengths out to 6.3 µm. Idler power was directly measured out to 5.41µm. Beyond this, idler generation was inferred from the observed signal. We present an analysis of operation in the presence of strong idler absorption.
Spin and population dynamics of photoexcited carriers in GaAs/AlGaAs and InGaAs/InP quantum wells is investigated from 5K to 300K, revealing transition between excitonic and free carrier spin-relaxation at intermediate temperatures. Localisation is found to prolong spin relaxation of excitons by two orders of magnitude.
Periodically-poled lithium niobate (PPLN) is proving to be a very versatile and effective nonlinear optical material. It has a high nonlinearity (20pm/V) and offers non-critical phase-matching over its entire transmission range. In the first experiments demonstrating synchronously-pumped parametric oscillation[1] in PPLN, the tuning range achieved using a 1047nm pump (from a mode-locked Nd:YLF laser) covered 1.67μm - 2.806μm (signal+idler), using 6mm long PPLN samples that we had fabricated by electric field poling. In the experiment reported here, we have used longer samples (19mm, fabricated by Crystal Technology). This has resulted in lower thresholds, now down to as low as ~8mW of mean pump power at 1047nm. We have also used shorter grating periods, thus allowing a considerable extension of tuning range, now covering 1.33μm - 4.81μ...
